Methods and compositions for treating stickies

ABSTRACT

The present invention provides for methods and compositions for removing stickies and pitch from papermaking fiber by first chemically treating the papermaking fiber with a composition of at least two of an oil-soluble or water-dispersible hydrophobic polymer, an oil soluble or water-dispersible surfactant having an HLB of about 1 to about 10, a tackifier, and an oil soluble or water-dispersible solvent then mechanically separating the agglomerated stickies and pitch from the papermaking fiber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/870,780,filed Jun. 6, 1997 now U.S. Pat. No. 5,936,024. The entire disclosure ofapplication Ser. No. 08/870,780 is considered as being part of thedisclosure of this application, and the entire disclosure of applicationSer. No. 08/870,780 is expressly incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

The present invention relates to methods and compositions for removingstickies and pitch from papermaking fiber by a chemically enhancedmechanical separation process.

BACKGROUND OF THE INVENTION

In recent years, there has been an increasing use of recycled fibers inthe paper industry due to environmental concerns, governmentlegislation, economic considerations, and the market demand for papercontaining recycled fiber. Since stickies contaminants are present invarying amounts in recycled paper, they often cause special problems atvarious stages of the papermaking process. These problems often include:

1 ) increased machine downtime due to breaks and required clean-up

2) reduced product quality due to picking, pinholes, and poor appearance

3) increased replacement costs for wires and felts

4) reduced converting and/or printing process efficiency

5) limited levels of fiber substitution

6) repulping difficulty

Stickies are generally a diverse mixture of polymeric organic materialswhich can stick on wires, felts or other parts of paper machines, orshow on the sheet as "dirt spots". The sources of stickies may bepressure-sensitive adhesives, hot melts, waxes, latexes, binders forcoatings, wet strength resins, or any of a multitude of additives thatmight be contained in recycled paper. The term "pitch" normally refersto deposits composed of organic compounds which are derived from naturalwood extractives, their salts, coating binders, sizing agents, anddefoaming chemicals existing in the pulp. Although there are somediscrete characteristics, there are common characteristics betweenstickies and pitch, such as hydrophobicity, low surface energy,deformability, tackiness, and the potential to cause problems withdeposition, quality, and efficiency in the process.

For the increased mandatory use of recycled fiber in the pulp and paperindustry, co-occurrence of stickies and pitch problems are oftenobserved. The materials of this invention have shown their ability toremove stickies from fiber furnish via agglomeration mechanisms andmechanical separation processes. It is believed that these materials canalso be used for pitch agglomeration and pitch removal from the fiberfurnish.

Several non-chemical approaches have been used in the paper industry tocombat stickies. These approaches include furnish selection, screening,cleaning, and thermal/mechanical dispersion such as dispergers orkneaders. However, each of these approaches has limitations. Furnishselection may reduce but not completely eliminate the stickies'contaminants in the system, while it will significantly increase thefurnish cost. Furthermore, paper companies will also tend to utilizelower grade furnishes to reduce raw material costs. Subsequently, evenmore contaminants are introduced into the papermaking system.

Stickies cannot be completely removed with screening equipment sinceminimum slot size is limited to 150 microns for throughput reasons.Finer screen may also cause a high level fiber loss with contaminantsremoval. Reverse and forward cleaning may not be effective for removingstickies due to the small density differences between stickies andwater. Thermal/mechanical dispersion units can enhance the breakup ofstickies, but cannot prevent the agglomeration downstream where problemsusually occur. In addition, this approach requires capital investmentcosts and energy expenditure.

Chemical treatment techniques for controlling stickies and pitch includedispersion/emulsification, detackification, wire passivation, andcationic fixation. Chemical treatments include mineral additives, alum,polyphosphates, emulsifiers, dispersants, water-soluble polymers, andcombinations thereof.

Typically, these agents are fed to the pulper, stock storage chestand/or applied to the process equipment surfaces where depositionsoccurred. These surfaces include paper machine foils, paper machinewires, wet press felts, dryer felts, Uhle boxes and calendar stacks.

SUMMARY OF THE INVENTION

The present invention is directed towards stickies and pitch removal bychemically enhanced mechanical separation processes. The stickies andpitch contained in the papermaking fiber are first treated chemicallyand removed subsequently through a mechanical separation process.

The chemicals employed in the present invention are either oil solubleor water dispersible. These chemicals include at least two of an oilsoluble or water-dispersible polymer, an oil soluble orwater-dispersible surfactant having an HLB of about 1 to about 10, atackifier, and an oil soluble or water-dispersible solvent.

DESCRIPTION OF THE RELATED ART

A number of chemicals have traditionally been used to treat stickies.Representative examples include a methyl cellulose derivative, a methylether cellulose derivative, polyvinyl alcohol and urea. M. R. Doshi in"Additives to Combat Sticky Contaminants in Secondary Fibers", TappiRecycling Paper: From Fiber to Finished Product, p. 519, 1991, discussesfive different additives for controlling stickies. These additivesinclude talc, solvents and dispersants, synthetic fibers, zirconiumcompounds and sequestering agents for excess alum. "Cost-Effective,Common Sense Approach to Stickies Control", T. J. Fogarty, Tappi J.,Vol. 76, No. 3, March 1993, provides an overview addressing controlmethods such as dispersion, detackification, cationic fixation, wirepassivation, and solvents to control stickies in recycled fiber.

All of these approaches will allow the stickies to either attach to thefiber surfaces or remain in the papermaking water system. For thestickies adhered to the fiber surfaces, they will eventually contaminatethe system when the fiber is recycled. Stickies remaining in the watersystem will cause problems later due to re-agglomeration, deposition,etc., especially for a closed loop system. In comparison, the presentinvention is able to make stickies agglomerates, which are not attachedto the fiber surfaces, and completely remove them from the papermakingsystem.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods and compositions for removingstickies and pitch from papermaking fiber comprising the steps of addingto the papermaking fiber in the pulper or stock storage chest acomposition comprising at least two of an oil soluble orwater-dispersible hydrophobic polymer, an oil soluble orwater-dispersible surfactant having an HLB of about 1 to about 10, atackifier, and an oil soluble or water-dispersible solvent, wherein thecomposition will cause the agglomeration of stickies and pitch, and amechanical separation of the stickies and pitch from the papermakingfiber.

The present inventor has discovered that the inventive two-step approachwill remove agglomerated stickies and pitch from the recycled fiberstock. Downstream of the mechanical separation stage, the stock containsfew stickies. This will allow for less expensive processing as otherchemical treatments are not needed to eliminate the detrimental effectsof the stickies and pitch deposits.

The oil soluble or water-dispersible hydrnphobic polymers that areuseful in the present invention are selected crir7arily for theirhydrophobicity and, in some measure, their it to provide tackiness tostickies and pitch in the aqueous phase. Examoles of these polymersinclude, but are not limited to, phenol formald-atyde resin having amolecular weight of about 300 to about 1750, F-eferably the molecularweight is about 300, available as Cardolite NC-511 from Cardolite.

The hydrophobic polymers useful in this nvention further include but arenot limited to mixtures of tackified styrene-isoprene-styrene andstyrene-butadiene based rubbers. These mixtures comprise by weight 15from about 11 to about 28% styrene-isoprene-styrene rubber having amolecular weight of about 135,000 and from ac out 11 to about 28%styrene-butadiene rubber, and from about 58 to 68 percent resintackifiers. Typically the weight ratio of styrene-isoprene-styrenerubber to styrene-butadiene rubber is less than or equal to 1. The totalamount of rubbers range from about 32 to 42 percent. The tackifierscomprise hydrocarbon resins, such as a low molecular weight aliphatic oraromatic hydrocarbon, a rosin-based resin tackifier, and a polyethylenepolyester resin. This mixture is available from Avery Dennison as AveryDennison AE-3610.

Other oil soluble or water-dispersible polymers useful in the methods ofthe present invention include, but are not limited to, alkylated vinylpyrrolidone polymers having molecular weights from about 7300 to about8600 and are available from ISP as Ganex V-220 and Ganex V-216;polymethacrylate available as Acryloid 966 from Rohm & Haas; and hydroxyterminated 1, 3-butadiene homopolymer available from Eif Atochem asPolybd R-45HT resin; perfluoroalkyl polymers having molecular weightfrom about 2300 to about 4300 available as Lodyne SP-101A and LodyneSP-35A available from Ciba-Geigy.

The oil soluble or water-dispersible surfactants have HLB from about 1to about 10. The surfactants useful in the present invention include butare not limited to ethylene oxide (EO)-propylene oxide (PO) blockcopolymers having an HLB of about 1 and a molecular weight of about 3800and an HLB of about 4 and a molecular weight of abcut 5000 availablefrom BASF as Pluronic L-101 and Pluronic L-122 respectvely; C₁₂ to C₁₄alcohol ethoxylate having an HLB of about 6 and C₁₂ to C₁₆ alcoholethoxylate having an HLB of about 4.4, both available from VistaChemical respectively as Alfonic 1214 GC-2 and Alfonic 1216-22; and C₁₁to C₁₅ secondary alcohol ethoxylate having HLB of about 8 and availableas Tergitol 15-S-3 from Union Carbide.

Other suitable surfactants include but are not limited to ethcxylatedpropoxylated fatty acids having HLB's from about 3 to about 4.5 ardmolecular weights of about 1300 to about 1400. This compound isavailable commercially as Pegol L31 Ditallate from Rhone-Poulenc;coconut diethanolamide having a molecular weight of about 200 to about350 from Witco as Varamide A2; and alkyl phenol ethoxylate having an HLBof about 4.6 available as Igepal CO-210 from Rhone-Poulenc. The presentinventor anticipates that alcohol ethoxylates having from about C₈ toabout C₂₂ will also be effective in the methods of the presentinvention.

The oil soluble or water-dispersible resin tackifiers useful in themethods of the present invention include but are not limited to rosinbased resin having a softening point of about 80 to about 86° C.available as Zonester 85 and terpene based resins having a softeningpoint of about 22 to about 118° C. available as Zonarez ALPHA 25,Zonarez 7115 and Zonarez B-115 from Arizona Chemical.

The oil soluble or water-dispersible solvents that are useful in thepresent invention are aliphatic hydrocarbons which include but are notlimited to 1-methyl-4-isopropenyl-1-cyclohexene having a molecularweight of about 135 and available from TR-Metro as d-limonene; aliphatichydrocarbons having molecular weights of about 120 to about 180available as 140 solvent from Ashland; toluene; decyl alcohol availableas Epal 10 from Ethyl Corp.; n-methyl-2-pyrrolidone available as NMPfrom ARCO and triethylene glycol.

Other suitable solvents include but are not limited to polybutene havinga molecular weight of about 350 to about 500 available from AMOCO asIndopol L-14; terpene dimer having a molecular weight of about 270available as Acintene SDO-ACP from Arizona Chemical; and an epoxidizedsoybean oil having a molecular weight of about 1000 available from C. P.Hall Company as Plasthall ESO.

For purposes of the present invention, the phrase "at least two of"refers to a composition comprising a polymer and a solvent; a polyrmerand a surfactant; a polymer and a tackifier; a solvent and a surfactantor a polymer, a tackifier, a solvent, and a surfactant; or anycombinations thereof. The terms polymer, solvent, tackifier andsurfactant may include one or more of the designated class of compounds.

The compositions of the present invention are generally employed in aweight ratio of 1:9 to 9:1. As such, when two components are present,their weight ratio will range from about 1:9 to 9:1. When threecomponents are present, the weight ratios of one will range from about1:9 to 9:1 to each of the other two components, and so on for fourcomponents when they are all present in the composition.

The compositions of the present invention may be added to the pulper orthe stock chest in an amount ranging from about 5 parts per millionparts oven dry (O.D.) fiber to about 10,000 parts per million parts O.D.fiber. Preferably, from about 50 to about 5,000 parts are added permillion part O.D. fiber. The effective amount of the composition to beadded depends on a number of variables including the pH of the system,hardness of the water, temperature of the water; additional additives,consistency of furnish, and quantity and type of stickies and pitch inthe furnish.

The compositions of the present invention may be compatible with otherpulp and papermaking additives. These include starches, titaniumdioxide, defoamers, wet strength resins, sizing aids and biocides.

The compositions of the present invention are effective at temperaturesranging from room temperature (≈75° F.) to about 180° F. Thesecompositions are effective at a pH range of about 3 to about 12.

The mechanical separation of the agglomerated stickies and pitch followsthe chemical treatment. This mechanical separation lies between thepulper or the stock storage chest and the headbox. These mechanicalseparation processes are performed with one or more of primary,secondary and tertiary screens; forward, reverse, and throughrowcleaners; flotation devices; and centrifugal devices.

The use of slotted screens is preferred in the methods of the presentinvention. Typically, mills employ a fine screen of 0.006 inch (152micron) to 0.012 inch (305 micron) slots. These finer diameter screenssometimes are problematic as their screening capacity sacrificesthroughput. The method of the present invention allow mill personnel toemploy a larger diameter screen to capture the agglomerated stickies andpitch particles without sacrificing throughput.

The data set forth below were developed to demonstrate the unexpectedresults occasioned by use of the present invention. The followingexamples are included as being illustrations of the invention and shouldnot be construed as limiting the scope thereof.

                                      TABLE I                                     __________________________________________________________________________    Formulation                                                                         Component #1                                                                              Component #2 Component #3                                   __________________________________________________________________________     1    1-Methyl-4-isopronenyl-                                                                   alkylphenol ethoxylate                                                                     EP-PO Block copolymer                             1-cyclohexene (MW = 136) avg. MW = 280, HLB = 4.6 avg. MW = 3800, HLB                                     = 1                                               2* Aliphatic hydrocarbons elkylphenol ethoxylate EO-PO block copolymer        MW = 128 to 176 avg. MW = 280, HLB = 4.6 avg. MW = 3800, HLB = 1                                            3 Aliphatic hydrocarbons rosin acid                                         esters EO-PO block copolymer                      MW = 128 to 176 softening point 82° C. avg. MW = 5000, HLB = 4                                       4 1-methyl-4-isopropenyl-1- rosin acid                                      esters EO-PO block copolymer                      cyclohexene (MW = 136) softening point 82° C. avg. MW = 5000,                                      HLB = 4                                           5 polybutene, MW = 350 polymethacrylate --                                    to 500 spec. grav. = 0.90 to 0.92                                             6 terpene dimer polymethacrylate --                                           MW = 270 spec. grav. = 0.90 to 0.92                                           7 polybutene, MW = 350 phenol formaldehyde resin --                           to 500 avg. MW = 302                                                          8 C.sub.10 alcohol, MW = 158 phenol formaldehyde resin --                      avg. MW = 302                                                                9 ethoxylated propoxylated phenol formaldehyde resin --                       fatty acid avg. MW = 302                                                     10 terpene dimer phenol formaldehyde resin --                                  MW = 270 resin, avg. MW = 302                                                11 polymethacrylate phenol formaidehyde resin --                               spec. grav. = 0.90 to 0.92 avg. MW = 302                                     12 polybutene, MW = 350 alkylated vinylpyrrolidone --                          to 500 polymer (avg. MW = 8600)                                              13 phenol formaldehyde alkylated vinylpyrrolidone --                           resin avg. MW = 302 polymer, avg. MW = 7300                                  14 terpene dimer coconut diethanolamide --                                     MW = 270 MW = 204 to 344                                                     15 alkylphenol ethoxylate EO-PO block copolymer aliphatic hydrocarbons                                       avg. MW = 280, HLB 4.6 avg. MW = 3800,                                      HLB = 1 MW = 128 to 176                          16 alkylphenol ethoxylate branched alcohol triethylene glycol                  avg MW = 280, HLB = 4.6 ethoxylate, avg MW = 332,                              HLB = 8                                                                     17 mixture of S-I-S and aromatic hydrocarbon --                                S-B copolymers avg. MW = 92                                                  18 mixture of S-I-S and linear alcohol C.sub.12 -C.sub.14 aromatic                                         hydrocarbon                                       S-B copolymers ethoxylate, HLB = 6 avg. MW = 92                              19 mixture of S-I-S and linear alcohol C.sub.12 -C.sub.14 1-methyl-4-iso                                   propenyl-                                         S-B copolymers ethoxylate, HLB = 6 1-cyclohexene, MW = 136                   20 mixture of S-I-S and alkylphenol ethoxylate 1-methyl-4-isopropenyl                                        S-B copolymers avg. MW = 280, HLB = 4.6                                     1-cyclohexene, MW = 136                          21 mixture of S-I-S and linear alcohol C.sub.12 -C.sub.16 1-methyl-4-iso                                   propenyl-                                         S-B copolymers ethoxylate, HLB = 4.4 1-cyclohexene, MW = 136                 22 polyterpene (softening linear alcohol C.sub.12 -C.sub.14 1-methyl-4-i                                   sopropenyl-                                       point 115° C. ethoxylate HLB = 6 1-cyclohexene, MW = 136                                            23 mixture of S-I-S and linear alcohol                                       C.sub.12 -C.sub.14 n-methyl-2-pyrrolidone,        S-B copolymers ethoxylate HLB = 6 NW = 99                                    24 polyterpene (softening 1-methyl-4-isopropenyl-                              point 25° C.) 1-cyclohexene, NW = 136                               __________________________________________________________________________     *Also contains perfluoroalkyl polymer, MW = 4236                              SI-S is styreneisoprene-styrene                                               SB is styrenebutadiene                                                   

Laboratory Pulper Agglomeration Test

An unbleached kraft paper, cut into 1"×2" pieces was repulped to 5%consistency at 140° F. (-60° C.) and neutral pH for 60 minutes using aFormax Hydrapulper, to make a clean, uncontaminated furnish. Thepressure-sensitive adhesive contaminated furnish was prepared using thesame procedure, except an adhesive tape (3M packaging tape, model No.3750-G) was attached to a portion of the unbleached kraft paper. For hotmelt and wax contaminants, these were added as solid particles directlyto the clean fiber immediately following repulping.

A laboratory pulper was then used to evaluate the agglomeration tendencyof stickies using the previously repulped furnish. For the studiesinvolving the pressure-sensitive adhesive, the adhesive contaminatedfurnish was employed, otherwise the clean furnish was used. The repulpedfurnish was placed in the laboratory pulper and diluted to 4%consistency at neutral pH. The furnish was heated to the desiredtemperature and the shear force applied at 1000 rpm. The contaminants,0.714% wt. based on O.D. fiber, were added to the vortex of the furnishand allowed to mix for approximately one minute. The average size of hotmelt and wax contaminants that were added to the pulper was about 200microns. The furnish containing the test contaminants was then treatedwith an agglomeration agent at the dosage of 2-20 pounds per ton basedon O.D. fiber. After 30 minutes treatment, the furnish was run across a0.006 inch flat screen to collect the stickies agglomerates. Theagglomerates were examined for particle size distribution using a Cue-2image analyzer.

                  TABLE II                                                        ______________________________________                                        Particle Size Distribution of Agglomerates for Hot Melt                         and Pressure-Sensitive Adhesive                                                                           Particle Size Distribution                         Particle Size Distribution of Pressure-Sensitive                              of Hot Melt Agglomerates* Adhesive Agglomerates*                             Treatment (microns) (microns)                                               ______________________________________                                        Untreated 434˜1570  248˜536                                                 @ 10 #/T  @ 20 #/T  @ 10 #/T                                                                              @ 20 #/T                                  Formulation #1   958˜3,548 1,932˜4,028   385˜1,044                                              627˜1,336                           Formulation #2   970˜3,180 1,526˜3,290   484˜1,201                                              770˜1,540                           Formulation #3 --   770˜1,540 -- --                                     Formulation #4 -- 1,134˜2,150 -- --                                     Formulation #5   916˜3,860   862˜3240 -- 305˜525                                                 Formulation #6   534˜1,486                                             1,106˜1,992 -- 225˜370        Formulation #7   778˜2,658 1,322˜2,254   289˜1,029                                              494˜1,275                           Formulation #8   996˜3,442 1,196˜2,178 377˜546                                                  242˜803                             Formulation #9 1,084˜3,500   576˜2,930 371˜848                                                  323˜1,087                           Formulation #10   890˜2,610   994˜2,732 351˜712                                                 237˜1,345                           Formulation #11 -- 1,256˜2,616 -- --                                    Formulation #12   537˜2,483   638˜1,983   357˜1,000                                             395˜742                             Formulation #13   656˜2,231   972˜2,552 282˜803                                                 321˜593                             Formulation #14   763˜3,099   524˜2,405   385˜1,235                                             314˜1,458                           Formulation #15   674˜2,784 1,864˜3,220 466˜841                                                 554˜1,110                           Formulation #16 1,218˜3,540 1,204˜4,062 331˜897                                                 717˜1,650                           Formulation #17   874˜2362 1056˜2649 375˜754 519.about                                          .962                                      Formulation #18   604˜1812 1267˜2869 386˜926 645.about                                          .1067                                   Untreated  82˜187 (@ 110° F.)                                                               56˜287 (@ 110° F.)                        94˜275 (@ 130° F.)  55˜336 (@ 130° F.)                                     Formulation #19 212˜434 (@ 110°                                 F.) 127˜345 (@ 110° F.)                  (10 #/T) 200˜394 (@ 130° F.) 116˜337 (@ 130°                                F.)                                                   Formulation #20 131˜413 (@ 130° F.) 264˜332 (@                                     130° F.)                                       (10 #/T)                                                                      Formulation #21 419˜926 (@ 130° F.) 329˜464 (@                                     130° F.)                                       (10 #/T)                                                                      Formulation #22 305˜768 (@ 110° F.) 165˜407 (@                                     110° F.)                                       (10 #/T)                                                                      Formulation #23 245˜546 (@ 110° F.) 149˜348 (@                                     110° F.)                                       (10 #/T)                                                                      Formulation #24 178˜442 (@ 110° F.) 163˜314 (@                                     110° F.)                                       (10 #/T)                                                                    ______________________________________                                         *Test Conditions: Temp.: 150 F.  pH 7˜8  Time: 30 min.  Shear: 1000     rpm                                                                      

Due to the variable nature of stickies, their melting points, softeningpoints, glass transition temperatures, tackiness and hydrophobicity willdiffer. As such, the repulping temperature, pH, time, shear force andchemical treatment all have an impact on stickies agglomeration.

As demonstrated in Table II, few noticeable hot melt agglomerates wereobserved when the temperature was below 140° F. without chemicaltreatments. Formulations #1 to 18 enhanced the hot melt agglomerationonly at the temperatures of 150° F. In general, the particle sizedistribution of hot melt agglomerates shifted to larger sizes as thedosage of treatment increased from 10 lbs. per ton to 20 lbs. per ton.Formulations 19 to 24 were very effective at agglomerating hot meltseven when the temperature was as low as 110° F.

                  TABLE III                                                       ______________________________________                                        Particle Size Distribution of Agglomerates for Mixed Stickies                                              Particle Size Distribution of                       Particle Size Distribution Pressure-Sensitive                                 of Hot Melt & Wax Adhesive & Wax                                             Treatment Agglomerates Temp. @  Agglomerates Temp. @                          (10 #/T) 140° F. (microns) 130° F. (microns)                  ______________________________________                                        Untreated 325˜1,005                                                                              263˜590                                          Formulation #1 385˜1,771 851˜1,390                                Formulation #2 581˜1,151 723˜926                                  Formulation #5 342˜1,172 --                                             Formulation #6 571˜1,290 --                                             Formulation #7 688˜1,153 545˜1,096                                Formulation #8 596˜1,250 674˜928                                  Formulation #9 543˜1,573 646˜1,069                                Formulation #10 538˜1,835 606˜1,048                               Formulation #12 536˜1,111 629˜982                                 Formulation #13 669˜822   801˜1,082                               Formulation #14 865˜1,292 816˜1,356                               Formulation #15 815˜1,646 848˜1,071                               Formulation #16 487˜963   629˜1,638                               Untreated 180˜939   60˜352                                        (130° F.) (130° F.)                                             Formulation #19 622˜1,599 248˜586                                 (130° F.) (130° F.)                                             Formulation #20 497˜1,365 314˜607                                 (130° F.) (130° F.)                                             Formulation #21 742˜1,997 372˜658                                 (130° F.) (130° F.)                                           ______________________________________                                    

As demonstrated in Table III, for formulations 1 to 16, hot melt-waxagglomeration was observed when the mixed stickies were treated at 140°F. or above. The increase in the minimal size of hot melt-waxagglomerates should improve the screen's removal efficiency. At aneutral pH, 1 30° F. and 10 pounds per ton of treatment, formulations#19 and 20 performed equally well and were more effective thanformulations #1 to 16. A similar trend was observed for thepressure-sensitive adhesive-wax agglomeration.

                                      TABLE IV                                    __________________________________________________________________________    Particle Size Distribution of Sticky Agglomerates Derived from                  Hot Melt, Pressure-Sensitive Adhesive and Wax                                       Particle Size                                                                           Particle Size                                                                           Particle Size                                       Treatment Distribution Temp. Distribution Temp. Distribution Temp.                                       (10#/T) @ 130° F. (microns) @                                         140° F. (microns) @ 150° F.                                     (microns)                                         __________________________________________________________________________    Untreated                                                                             255˜685                                                                           312˜674                                                                           375˜1,486                                     Formulation #1 647˜920   639˜1,156 805˜2,907                Formulation #2   381˜1,005   397˜1,057 654˜3,343                                       Formulation #5 457˜718   470˜1,78                                0 616˜1,840                                   Formulation #6 -- 361˜811 481˜2,440                               Formulation #7 419˜803 535˜918 617˜1,747                    Formulation #8 -- 369˜934 516˜1,351                               Formulation #9 708˜948 557˜939 402˜2,194                    Formulation #10 631˜875   388˜1,675 772˜1,845                                          Formulation #12 371˜679 320˜569                                  692˜2,673                                     Formulation #13 530˜812 592˜756 433˜2,263                   Formulation #14 400˜810   609˜1,123 871˜2,577                                          Formulation #15 416˜959   408˜1,1                                63 812˜2,017                                  Formulation #16 297˜759 601˜956 454˜1,528                   Formulation #21 --   346˜1,504 --                                     __________________________________________________________________________     Test Conditions:                                                              pH: 7˜8                                                                 Shear: 1000 rpm                                                               Consistency: 4%                                                               Time: 30 minutes                                                         

Table IV demonstrates that mixed stickies of hot melt/pressure-sensitiveadhesive/wax can be agglomerated at 130° F. or above when they aretreated with agglomeration agents. The average agglomerate sizeincreased with increasing temperature.

                  TABLE V                                                         ______________________________________                                        Particle Size Distribution of Mixed Stickies Agglomerates                       When Treated with Formulation #21 at Various Dosages                                  Particle Size Distribution of                                         Sticky Agglomerates (microns)                                                         Temp. @ 125°                                                                       Temp. @ 140°                                                                      Temp. @ 125°                            Treatment F. & pH 11 F. & pH 7 F. & pH 11                                   ______________________________________                                        Untreated  89˜700                                                                             130˜715                                                                            254˜766                                  Formulation #21 317˜943 230˜795   350˜1,082                 @ 2 #/T                                                                       Formulation #21 259˜815 268˜1,179 314˜1,164                 @ 5 #/T                                                                       Formulation #21 332˜934 346˜1,504 446˜1,836                 @ 10 #/T                                                                    ______________________________________                                    

As demonstrated in Table V, Formulation #21 proved very effective atagglomerating mixed stickies at pH 11 and a temperature of 125° F. Thisformulation was even more efficacious at temperatures of 140° F.Stickies agglomeration tendency was enhanced at a higher pH with thetreatment.

A laboratory study was conducted to evaluate the efficiency of stickiesremoval by a flat screen using the chemical agglomeration mechanism. Theexperimental procedure involved dosing laboratory pulpers with a knownquantity of stickies, including hot melt, pressure-sensitive adhesive,and wax, and performing the pulper agglomeration test for control andtreated runs. The rejects from screening (0.006 inch slot) werecollected, dried, and accurately weighed. The percent rejects level(i.e., % removal) could then be determined.

                  TABLE VI                                                        ______________________________________                                        Stickies Removal by a Flat Screen with                                          the Chemical Agglomeration Mechanism                                          Dosage of                                                                     Formulation #21 Temperature (° F.) pH % Stickies Removal             ______________________________________                                        0 lbs/T   125           11     67.2                                             2 lbs/T 125 11 100.0                                                          5 lbs/T 125 11 100.0                                                          10 lbs/T  125 11 100.0                                                        0 lbs/T 140  7  47.4                                                          2 lbs/T 140  7  80.7                                                          5 lbs/T 140  7 100.0                                                          10 lbs/T  140  7  78.0                                                        0 lbs/T 140 11  65.9                                                          2 lbs/T 140 11 100.0                                                          5 lbs/T 140 11  82.7                                                          10 lbs/T  140 11 100.0                                                      ______________________________________                                         Note: Stickies consisted of hot melt, pressuresensitive adhesive, and wax

As demonstrated on Table VI, due to stickies agglomeration, the percentof stickies removal with the treatment was consistently higher thanthose of the control runs. Under the tested conditions, an increase of20 to 30% removal was always obtained. This indicates that with thechemical treatment the stickies can be effectively removed by increasingtheir sizes with the aid of mechanical separation. By doing this,stickies can be removed from the papermaking system at an early stage,and will not cause problems downstream.

While this invention has been described with respect to particularembodiments thereof, it is apparent that numerous other forms andmodifications of this invention will be obvious to those skilled in theart.

The appended claims and this invention generally should be construed tocover all such obvious forms and modifications which are within the truespirit and scope of the present invention.

What is claimed is:
 1. A method for removing stickies and pitch frompapermaking fiber in a pulp and papermaking system comprising:adding tothe fiber a composition comprising at least two of a) an oil soluble orwater-dispersible, hydrophobic polymer, b) an oil soluble orwater-dispersible surfactant having an HLB of about 1 to about 10, c) atackifier, and d) an oil soluble or water--dispersible solventcomprising at least one of 1-methyl-4-isopropenyl-1-cyclolhexene,aliphatic hydrocarbons, toluene, decyl alcohol, triethylene glycol,polybutene, terpene dimer, n-methyl-2-pyrrolidone and epoxidized soybeanoil; and separating agglomerated stickies and pitch from the fiber. 2.The method of claim 1, wherein the composition includes at least one oilsoluble or water-dispersible, hydrophobic polymer comprising at leastone of mixtures of tackified styrene-isoprene-styrene andstyrene-butadiene based rubbers, phenol-formaldehyde resins, alkylatedvinyl pyrrolidones, polymethacrylates, perfluoroalkyl polymer, andhydroxy terminated 1,3-butadiene hoiiiopolymer.
 3. The method of claim2, wherein the mixtures of tackified styrene-isoprene-styrene andstyrene-butadiene based rubbers comprise from about 11 to about 28 wt %styrene-butadiene rubber and from about 11 to about 28 wt %styrene-isoprene-styrene rubber.
 4. The method of claim 3, wherein theweight ratio of the styrene-isoprene-styrene rubber to thestyrene-butadiene rubber is less than or equal to
 1. 5. The method ofclaim 3, wherein the mixtures of tackified styrene-isoprene-styrene andstyrene-butadiene further comprise a hydrocarbon and rosin-based resintackifier.
 6. The method of claim 2, wherein the phenol-formaldehyderesins exhibit a molecular-weight of from about 300 to about
 1750. 7.The method of claim 6, wherein the phenol-formaldehyde resins exhibit amolecular weight of about
 300. 8. The method of claim 2, wherein thealkylated vinyl pyrrolidones exhibit a molecular weight of from about7300 to about
 8600. 9. The method of claim 2, wherein thepolymethacrylates exhibit a specific gravity of from about 0.90 to about0.92.
 10. The method of claim 2, wherein the perfluoroalkyl polymersexhibit a molecular weight of from about 2300 to about
 4300. 11. Themethod of claim 1, wherein the composition includes at least onetackifier comprising at least one of rosin based resins and terpenebased resins.
 12. The method of claim 11, wherein said resins exhibit asoftening point of from about 20° C. to about 120° C.
 13. The method ofclaim 1, wherein the composition includes at least one surfactantcomprising at least one of an ethylene oxide-propylene oxide blockcopolymer, alcohol ethoxylate, ethoxylated propoxylated fatty acid,Coconut diethanolamide, and alkyl phenol ethoxylate.
 14. The method ofclaim 13, wherein the surfactant comprises at least one of an ethyleneoxide-propylene oxide block copolymer exhibiting an HLB of about 1 and amolecular weight of about 3800, an ethylene oxide-propylene oxide blockcopolymer exhibiting an HLB of about 4 and a molecular weight of about5000, a C₁₂ to C₁₄ alcohol ethoxylate exhibiting an HLB of about 6, aC₁₂ to C₁₆ alcohol ethoxylate exhibiting an HLB of about 4.4, a C₁₁ toC₁₅ secondary alcohol ethoxylate exhibiting an HLB of about 8, anethylene oxide propylene oxide fatty acid exhibiting an HLB of fromabout 3 to about 4.5 and a molecular weight of from about 1300 to about1400, a coconut diethanolamide exhibiting a molecular weight of fromabout 200 to about 350, and an alkyl phenol ethoxylate exhibiting an HLBof about 4.6.
 15. The method of claim 1, wherein the compositionincludes at least one solvent comprising at least one of aliphatichydrocarbons exhibiting molecular weights of from about 120 to about180, a polybutene exhibiting a molecular weight of from about 350 toabout 500, a terpene dimer exhibiting a molecular weight of about 270,and an epoxidized soybean oil exhibiting a molecular weight of about1000.
 16. The method of claim 1, wherein the composition is added in anamount ranging from about 5 parts to about 10,000 parts per millionparts oven dry fiber.
 17. The method of claim 16, wherein thecomposition is added in an amount ranging from about 50 parts to about5,000 parts per million parts oven dry fiber.
 18. The method of claim 1,wherein the pulp and papermaking system to which the composition isadded has a pH of about 3 to about
 12. 19. The method of claim 1,wherein the pulp and papermaking system to which the composition has atemperature of about 50° F. to about 180° F.
 20. The method of claim 1,wherein the separating agglomerated stickies and pitch from the fiber isperformed mechanically.
 21. The method of claim 20, wherein theseparating is performed with a device comprising a means selected fromthe group consisting of screening, cleaning, flotation, andcentrigation.
 22. A stickies and pitch agglomeration compositioncomprising:1) at least two of a) an oil soluble or water-dispersible,hydrophobic polymer, b) an oil soluble or water-dispersible surfactanthaving an HLB of about 1 to about 10, c) a tackifier, and d) an oilsoluble or water-dispersible solvent comprising, at least one of1-methyl-4-isopropenyl-1-cyclohexene, aliphatic hydrocarbons, toluene,decyl alcohol, triethylene glycol, polybutene, terpene dimer,n-methyl-2-pyrrolidone and epoxidized soybean oil; and 2) paper fiber.23. The composition of claim 22, including at least one oil soluble orwater-dispersible, hydrophobic polymer comprising at least one ofmixtures of tackified styrene-isoprene-styrene and styrene-butadienebased rubbers, phenol-formaldehyde resins, alkylated vinyl pyrrolidones,polymethacrylates, perfluoroalkyl polymer, and hydroxy terminated1,3-butadiene homopolymer.
 24. The composition of claim 23, wherein themixtures of tackified styrene-isoprene-styrene and styrene-butadienebased rubbers comprise from about 11 to about 28 wt % styrene-butadienerubber and from about 11 to about 28 wt % styrene-isoprene-styrenerubber.
 25. The composition of claim 24, wherein the weight ratio of thestyrene-isoprene-styrene rubber to the styrene-butadiene rubber is lessthan or equal to
 1. 26. The composition of claim 24, wherein themixtures of tackified styrene-isoprene-styrene and styrene-butadienefurther comprise a hydrocarbon and rosin-based resin tackifier.
 27. Thecomposition of claim 23, wherein the phenol-formaldehyde resins exhibita molecular weight of from about 300 to about
 1750. 28. The compositionof claim 27, wherein the phenol-formaldehyde resins exhibit a molecularweight of about
 300. 29. The composition of claim 23, wherein thealkylated vinyl pyrrolidones exhibit a molecular weight of from about7300 to about
 8600. 30. The composition of claim 23, wherein thepolymethacrylates exhibit a specific gravity of from about 0.90 to about0.92.
 31. The composition of claim 23, wherein the perfluoroalkylpolymers exhibit a molecular weight of from about 2300 to about 4300.32. The composition of claim 22, including at least one tackifiercomprising at least one of rosin based resins and terpene based resins.33. The composition of claim 32, wherein said resins exhibit a softeningpoint of from about 20° C. to about 120° C.
 34. The composition of claim22, including at least one surfactant comprising at least one of anethylene oxide-propylene oxide block copolymer, alcohol ethoxylate,ethoxylated propoxylated fatty acid, coconut diethanolamide, and alkylphenol ethoxylate.
 35. The composition of claim 34, wherein thesurfactant comprises at least one of an ethylene oxide-propylene oxideblock copolymer exhibiting an HLB of about 1 and a molecular weight ofabout 3800, an ethylene oxide-propylene oxide block copolymer exhibitingan HLB of about 4 and a molecular weight of about 5000, a C₁₂ to C₁₄alcohol ethoxylate exhibiting an HLB of about
 6. a C₁₂ to C₁₆ alcoholethoxylate exhibiting an HLB of about 4.4. a C₁₁ to C₁₅ secondaryalcohol ethoxylate exhibiting an HLB of about 8, an ethylene oxidepropylene oxide fatty acid exhibiting an HLB of from about 3 to about4.5 and a molecular weight of from about 1300 to about 1400, a coconutdiethanolamide exhibiting a molecular weight of from about 200 to about350, and an alkyl phenol ethoxylate exhibiting an HLB of about 4.6. 36.The composition of claim 22, including at least one solvent comprisingat least one of aliphatic hydrocarbons exhibiting molecular weights offrom about 120 to about 180, a polybutene exhibiting a molecular weightof from about 350 to about 500, a terpene dimer exhibiting a molecularweight of about 270, and an epoxidized soybean oil exhibiting amolecular weight of about
 1000. 37. The composition of claim 22, havinga pH of about 3 to about
 12. 38. The composition of claim 22, whereinthe ratio of component 1) to component 2) ranges from about 5 parts toabout 10,000 parts per million, wherein component 2) is measured asparts oven dry fiber.
 39. The composition of claim 38, wherein the ratioof component 1) to component 2) ran-es from about 50 parts to about5,000 parts per million, wherein component 2) is measured as parts ovendry fiber.